Separation method and assembly for process streams in component separation units

ABSTRACT

A method for removing contaminants from an process stream that includes the use of reticulated material to filter the process stream. The reticulated material also facilitate process stream flow distribution in process units. The reticulated material can be packed with a void space between a substantial number of the reticulated material that can be varied to enhance filtration and flow distribution. The method of filtering also provides a method of removing contaminants leaving process equipment. The methods can be used on a variety of process streams and process equipment. The reticulated material can include ceramics, metallic materials, and chemical vapor deposition elements. The reticulated material can be of various shapes and sizes, and can also be catalytically active.

RELATED APPLICATION

This application is a continuation application of, and claims thebenefit of, U.S. application Ser. No. 16/298,978, filed Mar. 11, 2019,which is a continuation of, U.S. application Ser. No. 12/786,165, filedMay 24, 2010, which is a continuation of, U.S. application Ser. No.11/136,631, filed May 24, 2005, which is a continuation-in-part of U.S.application Ser. No. 10/396,851, filed Mar. 25, 2003. Furthermore, U.S.application Ser. No. 16/298,978, filed Mar. 11, 2019 is a continuationapplication of, and claims the benefit of U.S. application Ser. No.12/786,140, filed May 24, 2010, which is a divisional of, U.S.application Ser. No. 11/136,631, filed May 24, 2005, which is acontinuation-in-part of U.S. application Ser. No. 10/396,851, filed Mar.25, 2003.

BACKGROUND Field of the Invention

The invention relates to a method of providing filtration ofcontaminants from process streams. In another aspect, this inventionrelates to a method for providing flow distribution of process streamsin process units. In yet another aspect, this invention providesfiltration or flow distribution or both while concurrently catalyzing atleast one reaction to at least partially remove and/or convert certainchemical species within the process stream.

Description of Related Art

Contaminants in process streams can be deleterious to processes and alsoto process units. Contaminants can damage process units, potentiallyresulting in an environmental or safety incident. Contaminants can alsodamage processes by decreasing efficiencies within processes, stoppingproduction, affecting the specifications of products, or the like.Contaminants can be found in all types of process streams, such as feedstreams, discharge streams, or effluent streams. Contaminants can affectvarious types of process units, such as reactors, extractors,distillation columns, scrubbers, tail gas treaters, incinerators,exchangers, boilers, condensers, and the like.

Process units may be configured such that process streams in the unitflows vertically downward or upward or both. Alternatively, processstreams in the unit may flow radially from the center out or from theexternal part of the unit to the center or both.

Reactors are one type of process unit. Many reactors include discretesolid catalyst particles contained in one or more fixed beds. Catalystbeds are typically very efficient at trapping contaminants in processstreams fed to the catalyst bed. Such catalyst beds, however, canquickly become clogged by these trapped contaminants. As the bed becomesclogged, pressure drop across the process unit rises resulting ineventual premature shutdown of the process unit.

Partly to mitigate this problem, catalyst bed process units as well asnon-catalyst bed process units are often supplemented with conventionalretention material beds that are somewhat less resistant to clogging.These conventional retention material beds are typically located at theinlet to the process unit. In the case of catalyst bed process units,the conventional retention material beds are typically inert to thereactions in the catalyst bed. These conventional retention materialbeds can be somewhat effective in trapping or filtering all or somecontaminants such as dirt, iron oxide, iron sulfide, asphaltenes, cokefines, catalyst fines, salts, acidic impurities, sediments or otherentrained foreign particulate material in the process stream entering,within or leaving the process unit. The trapping of the contaminants isto prevent undesirable material from clogging or poisoning or otherwiseharming the process unit. When these conventional retention materialbeds are inert they are typically made of conventional ceramic materialsin the form of pellets, rings, saddles or spheres and typically must beresistant to crushing, high temperatures and/or high pressures. Whilethese conventional retention material beds can be somewhat effective inpreventing the process unit from being clogged, the conventionalretention material beds themselves eventually become clogged.

Conventional retention material beds may also facilitate flowdistribution of the process stream in a direction perpendicular to theflow of the process stream across the process unit. Such behavior willbe referred to herein as perpendicular flow distribution. As an example,in an upflow or down flow process unit, the process stream flow is inthe axial direction and the perpendicular flow distribution is in theradial direction.

To increase the efficiency of conventional retention material beds,graduated layers of these materials in different sizes and shapes alongwith perforated discs, or screen baskets, have been used to retard theprocess unit from becoming clogged with contaminants such as dirt, ironoxide, iron sulfide, asphaltenes, coke fines, catalyst fines, sediments,or other entrained foreign particulate material.

Conventional retention material beds exposed to contaminants at theinlet to a process unit will eventually become clogged withcontaminants. As this happens, the pressure drop across the process unitrises, resulting in the eventual shutdown of the unit. When this happensin catalyst bed process units, it is typical that part of the catalystbed itself becomes somewhat or completely clogged with contaminants.After such shutdown of the process unit, skimming, or removal, of theclogged portion of the conventional retention material, as well as theclogged portion of the catalyst bed, is required.

In addition to clogging by contaminants in the process stream,polymerization of polymer precursors, e.g., diolefins, found in theprocess streams fed to catalyst bed process units may also foul, gum orplug such process units. In particular, two mechanisms ofpolymerization, free radical polymerization and condensation-typepolymerization, may cause catalyst bed fouling, gumming or plugging. Theaddition of antioxidants to control free radical polymerization has beenfound useful where the process stream has encountered oxygen.Condensation polymerization of diolefins typically occurs after anorganic-based feed is heated. Therefore, filtering prior to the processstream entering the catalyst bed process unit may not be helpful toremove these foulants as the polymerization reactions generally takeplace in the unit.

It is highly desirable to have retention materials that do not just clogwith contaminants but efficiently and effectively filter contaminantsfrom the process stream. Efficiency relates to the percent ofcontaminants removed by such materials from the process stream, as wellas, to the range of sizes of contaminants that can be removed by suchmaterials. Effectiveness relates to the extent that such materials donot impede the flow of the decontaminated process stream through theretention materials. Such materials would desirably remove virtually allcontaminants within a broad range of sizes from the process stream,while not causing an unacceptable pressure drop increase across theprocess unit. It is also highly desirable to have retention materialsthat promote perpendicular flow distribution. The method of the presentinvention for filtration and flow distribution for process streams, whencompared with previously proposed prior art methods, has the advantagesof providing highly efficient and highly effective filtering ofcontaminants; increasing the life and activity of catalysts in catalystbed process units; decreasing catalyst losses; enhancing productselectivities, increasing throughput/productivity, allowing for theoptimization of process unit configuration; improving the perpendicularflow distribution of process streams into and within process units andeliminating the need to take process units off-line when conventionalretention material beds have clogged to the point that pressure dropacross units have risen to unacceptable levels. These benefits willresult in both capital and operating cost savings, reduced downtimes,increased process unit performance and extended process unit operatingtime.

Weaknesses of conventional retention material beds are that they areneither particularly efficient nor particularly effective as filters.Conventional retention material beds are typically efficient at removingsome contaminants from the process stream for a limited period of time.The contaminants so trapped are typically those about 50 microns andlarger. The effectiveness of conventional retention material bedssuffers due to eventual clogging, which prevents flow of thedecontaminated process stream through the conventional retentionmaterial beds and leads to unacceptable increase in process unitpressure drop. Furthermore, conventional retention material beds appearto trap contaminants within about the top six to twelve inches of depth.Deeper beds of conventional retention materials do not increase thetrapping capacity of these materials. Therefore, the art has soughtfiltration methods that remove particulate contaminants smaller than 50microns, that filter particulate contaminants while allowing the freeflow of decontaminated process streams with no significant rise inprocess unit pressure drop and that have a filtering capacity thatincreases with bed depth, regardless of bed depth.

Disadvantages associated with current perpendicular flow distributiondesigns and methods in process units may result in poor distributionwithin the process unit. Clogging or other fouling such as that causedby particulate contaminants or the products of undesired polymerizationreactions may also cause maldistribution. The maldistribution may resultin channeling and corresponding bypassing of portions of the processunit, reduction in the efficiency of contaminant removal and reductionin unit efficiency. Usually, a maldistribution problem is also evidencedby so-called temperature hot-spots. Such hot-spots can, for example,lead to increased coking and reduced activity in catalyst bed processunits. Besides maldistribution problems and coking, the increase inpressure drop may cause catalyst breakdown as a result of attrition.Therefore, the art has sought a perpendicular flow distribution methodthat may distribute the process stream more uniformly within the processunit, provide efficient filtering of contaminants, reduce the occurrenceof hot-spots, minimize catalyst attrition, and reduce fouling caused byundesired polymerization reactions.

U.S. Pat. Nos. 6,258,900 and 6,291,603, both of which are incorporatedby reference in their entireties, describe reticulated ceramic materialsthat are used to filter and distribute organic feed streams in achemical reactor. A need exists for filtering and flow distributioncapabilities for other types of process streams besides organic-basedstreams and for other types of process units besides chemical reactors.

It is desirable for the filtering and flow distribution methods for allprocess streams and all process units to increase the filteringefficiency and effectiveness of materials utilized to removecontaminants from process streams, to improve perpendicular flowdistribution within process units, to have unit run length determined byfactors other than pressure drop increase, to minimize pressure dropsacross process equipment, and to maximize process safety and minimizeenvironmental concerns arising from catalyst bed channeling and flowmisdistribution, temperature hot-spots and process unit shutdowns andstart-ups.

Component separation units are a specific type of process unit that havetraditionally been used in laboratories, pilot plants and industrialfacilities to separate process streams into component process streamshaving desired compositions. With regard to any component separationunit, a “process stream” can refer to a feed stream, “component processstreams” can refer to product streams from the unit and “phases” canrefer to individual liquid or vapor phases within the unit. Duringcomponent separation, a phase moving in one direction and a phase movingin the opposite direction are contacted with one another within thecomponent separation unit to effectuate mass transfer at the interfacebetween the phases. Component separation is accomplished as a result ofthis mass transfer. As a result of the mass transfer, one or moreprocess streams are separated to form one or more component processstreams each having desired compositions. Typically, a plurality oftrays and/or packing elements are positioned within the unit tofacilitate contact between the phases and mass transfer between thephases. The trays are typically stacked horizontally with respect to oneanother, while the packing elements are randomly loaded or formed into astructured shape. Randomly loaded packing elements generally do not haveany specified orientation relative to one another, while structuredelements have a specific overall shape and relative orientation.

Examples of component separation units include, for example,distillation units, chromatographic units, absorbers, extractors andcombinations thereof. Distillation units achieve component separationbased on the differences in boiling points of the species present in theprocess streams fed to the unit. Distillation units include, forexample, columns, fractionators, splitters, semi-continuous units,continuous units, flash units, batch distillation units, strippers,rectifiers, extractive distillation units, azeotropic distillationunits, and vacuum distillation units. Absorbers and extractors arecontacting units in which vapor and liquid phases are contacted anddesired component separation is achieved based on the affinity ofcomponents in one phase to the components in the other phase. Forexample, a process stream containing components A and B may enter such aunit at one position while another process stream containing C may enterthe unit at another position. One of these streams is typically liquidwhile the other can be liquid or vapor. Now assume component B has amuch greater affinity for component C than for component A. Intimatecontacting of the two streams in a properly designed and operatedcontacting unit will result in creating one product stream containingcomponent A with a essentially no component B and a second productstream containing component C and essentially all of component B.Commercial use of such a unit might be driven by the difficulty ofdirectly separating B from A versus of separating B from C. In thisexample the first product stream would be termed the desorbant and thesecond product stream would be termed the absorbant. Specific examplesof absorber units include continuous absorbers, temperature swingabsorbers, pressure swing absorbers, purge/concentration swing absorbersand parametric pumping. Extractors are contacting units in whichimmiscible liquid phases are contacted and component separation isachieved using a mass separating agent. In the example above, thecomponent C in the second process stream would be the mass separatingagent. An example of an extractor unit is an aromatics extraction unitwherein a hydrocarbon stream containing aromatic species andnon-aromatic species are contacted with a mass separating agent such assulfolane or morpholine and efficient contacting of these two immiscibleliquids results in extraction of the aromatic species from thehydrocarbon steam into the stream containing the mass separating agent.Component separation units can also include a zone of catalyticmaterials to facilitate desired chemical reactions in the componentseparation unit. Examples of such include reactive distillation unitsand extractive distillation units. Examples of conventional unitinternals used to achieve or enhance separation in component separationunits include, for example, trays, randomly packed rings or saddles,structured packing having meshes, monoliths, gauzes and the like,collectors, distributors, downcomers, wall wipers, support grids andhold down plates.

Inside a component separation unit, there is repeated intimate contactbetween the rising phase and the falling phase. This contact isfacilitated by the trays and/or packing materials. Each section of traysor depth of packing material may approximately represent a number of“theoretical stages” of separation. The component separation unitinternals are designed and positioned within the component separationunit to produce the appropriate number of “theoretical stages” that willachieve the desired separation.

In distillation units the repeated contact between the phases ultimatelyresults in a vapor phase consisting of higher volatility, lower boilingpoint species and a liquid phase consisting of lower volatility, higherboiling point species. This mass transfer between phases is driven bythe differences between the boiling points of the species in the phases.Species with lower boiling points rise and components with higherboiling points fall. Upon creation of the one or more phases of desiredcomposition, a portion of the vapor phase is typically recovered as anupper component process stream, and the remaining portion is condensedand passed as a reflux phase back into the distillation unit for furthermass transfer. Likewise, a portion of the liquid phase is recovered as alower component process stream, and the remaining portion is reboiled(i.e., vaporized) and returned to the distillation unit for further masstransfer. In addition, one or more component process streams can berecovered from the distillation unit at any location between the top andbottom of the distillation unit.

In component separation units, it is highly desirable to achieveefficient and cost effective separation within the unit. It is alsohighly desirable to achieve low pressure drop within the unit and a lowHETP (height equivalent to a theoretical plate (or stage)) number forthe unit. The degree of separation achieved by the unit may be affectedby, among other factors, the amount of contact between the phases, thenumber of trays used, the amount and type of packing material used, thetemperature and pressure at which the unit is operated, and thedifferences between the boiling points or other relevant separationcharacteristics of the species contained within the phases. Separationmay also be affected by, for example, the design of the trays, the useof distributors in the unit to promote uniform distribution of phasesacross the cross-sectional area of the unit, and the design of thepacking materials.

Prior art packing materials within component separation units have beeneither randomly loaded or structured. Randomly loaded or “loose”packing, although less costly than structured packing material, has beenshown to have high pressure drop or low mass transfer characteristics,and suffer from poor phase distribution which results in poor separationefficiency in the unit. Also, prior art units that have utilized traysor “loose” packing materials have proven to be prone to corrosion andfouling and have provided inefficient separation. As a result, prior artloose packing technology gave way to the development of highlyengineered structured packing technology. Structured packing materialscan provide improved or separation efficiency; however, themanufacturing of structured packing material requires sophisticatedmachineries, engineering expertise and fabrication skills to designlarger units to perfection. Further, these materials are generally moreexpensive to fabricate and require more unit down time for installationthan random packing. Even though they are more costly, structuredpacking materials are often used in place of random packing because theyprovide higher production rates than existing units due to betterpressure drop and mass transfer characteristics. The use of structuredpacking materials, however, has generally been limited to processes thatare not subject to fouling or corrosion. Structured packing is moreexpensive and difficult to install, and so its use in processes wherefouling or corrosion would necessitate more frequent replacement iseconomically unattractive.

Accordingly, prior to the development of the present invention, therehas been no method and apparatus for separating process streams intocomponent process streams having desired compositions in a componentseparation unit which provides the desirable characteristics and/orlevels of: efficient separation at a low HETP value; relatively lowpressure drop; resistance to fouling and/or corrosion; low fabricationand installation costs; ease of replacement; and improved overallperformance and production. Therefore, the art has sought a method andapparatus for improving the separation of process streams into desiredcomponent process streams via distillation, absorption and/or extractionwhich: does not cause relatively large pressure drops; displays moreefficient separation at a low HETP number; requires less complex andexpensive design, fabrication, installation, operation and maintenance,resists fouling and corrosion, can be easily replaced and exhibitsoverall improved performance and production.

SUMMARY OF INVENTION

In accordance with the invention, the foregoing advantages have beenachieved through the present method of filtering a process stream, fordistributing a process stream within a process unit and foraccomplishing one or both while concurrently catalyzing desiredreactions. Yet another embodiment of the invention is separating one ormore process streams into one or more component process streams havingdesired compositions in a component separation unit using specifiedforms of cellular solid materials. CELLDIST will be the name used toidentify the specific forms of cellular solid materials used in thepresent invention. CELLDIST materials are three-dimensional cellularsolids. Cellular solids are materials comprised of solid components ormaterials and cells. (“Cells” and “pores” are, for the purpose of thisapplication, synonyms.) The solid material can be comprised of ceramics,metals, polymers and mixtures thereof. The cells can be open or closedor a combination of both. Open cells have windows into the cell saidwindows being of a size equal to or less than the size of the cellitself. Open-cell materials have passages between the cells through thewindows in the cell. Closed-cell materials have no windows and nopassages between cells. There are two basic structural forms of cellularsolids: two-dimensional and three-dimensional. Two-dimensional cellularsolids have cells that are translated in two dimensions. These typicallyform non-interconnected parallel channels. Honeycombs and monoliths areexamples of two-dimensional cellular solids. There are two basicstructural forms of three-dimensional cellular solids: periodic andstochastic. Three-dimensional periodic cellular solids are characterizedby a unit cell that is translated throughout the structure withthree-dimensional periodicity. Examples include ordered cell arrays suchas hollow spheres and truss and lattice structures. Stochastic cellularsolids have three-dimensional geometry with variation of cell sizes andshapes. These materials cannot be characterized by a single repeatedunit cell. The randomness of the topology of these materials leads tothe label “stochastic.” An example of an open-cell stochastic cellularsolid is ceramic foam. CELLDIST materials need not be purely stochasticnor purely periodic in topology. CELLDIST materials may be intentionallyor unintentionally a combination of the two, the latter due to theimprecision of nature when it comes to attaining perfect periodicity andthe opportunity at some level to formulate stochastic materials thathave some semblance of periodicity. Cellular solids with substantiallyopen cells are also called reticulated materials.

CELLDIST materials must also satisfy the requirements of separation. Therequirements of separation of the present invention are driven by theneed to achieve satisfactory capacity, phase contacting and pressuredrop in component separation units. The requirements of separationrequire that the CELLDIST materials exhibit sufficiently open cells andlow relative density. Recognizing the possible existence of an amount ofclosed cells in the CELLDIST material, sufficiently open cells havewindows into sufficient open cells such that the average window size isgreater than 10% of the size of the average cells (including open andclosed cells), preferably averaging greater than 40% of the size of theaverage cell. Relative density is the density of the cellular soliddivided by the density of the solid material itself. Relative density islow if it is 50% or less, preferably 30% or less.

In accordance with the invention, component separation units are aspecific type of process unit used to separate process streams into oneor more component process streams having desired compositions. Withregard to any component separation unit, a “process stream” can refer toa feed stream, “component process streams” can refer to product streamsfrom the unit and “phases” can refer to individual liquid or vaporphases within the unit. Examples of component separation units relevantto the invention include, for example, distillation units, adsorbers,extractors and combinations thereof. During component separation in, forexample, a distillation unit, a phase moving in one direction and aphase moving in the opposite direction are contacted with one anotherwithin the component separation unit to effectuate mass transfer at theinterface between the phases. During component separation in, forexample, an adsorption unit, mass transfer is accomplished by causingdesired species from one or more fluid phases to be adsorbed on thesurface of suitably activated solid materials, including CELLDISTmaterials, packed within the unit. During component separation in, forexample, an extraction unit, fluid phases are contacted within the unitto achieve desired mass transfer between the phases. Componentseparation is accomplished as a result of this mass transfer. As aresult of the mass transfer, one or more process streams are separatedto form one or more component process streams each having desiredcompositions.

Examples of component separation units relevant to the inventioninclude, for example, distillation units, absorbers, extractors andcombinations thereof. Distillation units achieve component separationbased on the differences in boiling points of the species present in theprocess streams fed to the unit. Distillation units include, forexample, distillation columns, fractionators, splitters, semi-continuousunits, continuous units, flash units, batch distillation units,strippers, rectifiers, extractive distillation units, azeotropicdistillation units, and vacuum distillation units and combinationsthereof. Absorbers and extractors are contacting units in which one ormore fluid phases are contacted and desired component separation isachieved based on the affinity of components in one phase to either thecomponents in the other phase or to suitably activated solid adsorbentmaterials packed in the unit. For example, a process stream containingcomponents A and B may enter such a unit at one position while anotherprocess stream containing C may enter the unit at another position. Oneof these streams is typically liquid while the other can be liquid orvapor. Now assume component B has a much greater affinity for componentC than for component A. Intimate contacting of the two streams in aproperly designed and operated contacting unit will result in creatingone product stream containing component A with a essentially nocomponent B and a second product stream containing component C andessentially all of component B. Commercial use of such a unit might bedriven by the difficulty of directly separating B from A versus ofseparating B from C. Specific examples of absorber units includecontinuous absorbers, temperature swing absorbers, pressure swingabsorbers, purge/concentration swing absorbers and parametric pumping.Extractors are contacting units in which immiscible liquid phases arecontacted and component separation is achieved using a mass-separatingagent. In the example above, the component C in the second processstream would be the mass-separating agent. An example of an extractorunit is an aromatics extraction unit wherein a hydrocarbon streamcontaining both aromatic species and non-aromatic species are contactedwith a mass separating agent such as sulfolane or morpholine andefficient contacting of these two immiscible liquids results inextraction of essentially all of the aromatic species from thehydrocarbon stream into the stream containing the mass separating agent.Component separation units can also include a zone of catalyticmaterials to facilitate desired chemical reactions in the componentseparation unit. Examples of such include reactive distillation unitsand extractive distillation units.

The present invention advantageously provides a method of removingcontaminants from a contaminated process stream. The method preferablyis performed by passing the process stream over a plurality ofreticulated elements in a process unit. The reticulated elements arerandomly packed in the process unit such that there is significant voidspace between each reticulated element to enhance filtration ofcontaminants on a surface of the reticulated elements while allowing thedecontaminated process stream to pass unimpeded through the plurality ofreticulated elements. A surface can include an inner surface and anouter surface. Reticulated elements made in accordance with the presentinvention will have more inner surface area available for filtering thanouter surface area. Reticulated elements can include foam materials andmonolith materials. Foam materials generally have a random pattern,while the monoliths have a more uniform pattern. The reticulatedelements can be made from any commercially available materials, forexample, zirconia toughened alumina, commonly referred to as ZTA. ZTA isavailable, in a ceramic foam, from Fiber Ceramics, Inc. headquartered inCudahy, Wis. Another suitable type of ceramic is a monolith, which ismanufactured by Corning, Inc. headquartered in Corning, N.Y. The processstream can be a liquid stream, a vapor phase, or a combination of bothphases, and the contaminants can include dirt, iron oxide, iron sulfide,asphaltenes, coke fines, soot, catalyst fines, acidic impurities,sediments or other entrained foreign particulate matter, salts indistillation columns, particulates in gas streams, or sulfur or sulfidesfrom tail gas units. The process stream can also be an organic-basedprocess stream. The reticulated elements should be provided in an amountsufficient to remove some or all of the contaminants from the processstream. Another feature of the present invention may include the step ofproviding a decontaminated process stream for further processing.

More particularly, the invention relates to a process for improvingstream quality of process streams entering to process units. Anexemplary example includes improving stream quality of organic-basedprocess streams going to catalytic bed process units. Preferably, thecatalytic bed process units use discrete, solid element, fixed catalystbeds. The catalytic bed process units can include hydrotreater,hydrorefiner, hydrocracker, reformer, alkylation, dealkylation,isomerization, oxidation, esterification, and polymerization reactors.The discrete solid catalyst particles may be contained in one or morefixed beds and in either an upflow, down flow or radial flow design.

In addition to catalytic bed process units, the reticulated elements ofthe present invention can be used to remove contaminants from othertypes of process equipment. Such process equipment can includeincinerators, scrubbers, tail gas treaters, and distillation columns andany manufacturing units that operate in a continuous fashion. When usedto remove contaminants in a distillation column, the reticulatedelements can be placed in the bottom of, or at any position in, thedistillation column to act as a filter to remove salts or othercontaminants from the distillation process. Removal of salts or othercontaminants will reduce the pressure drop across the tower, allow forbetter separation efficiency in the column, and increase the timebetween downtimes typically required to remove these salts or othercontaminants from the column.

The present invention also advantageously provides a method ofperpendicular flow distribution in process units. This perpendicularflow distribution method includes providing one or more reticulatedelements in the process unit. When only one reticulated element is used,it is typically large enough to effectively span the process unit. Whenmultiple reticulated elements are used, they are typically arranged in arandomly packed bed. Regardless of the configuration of the reticulatedelements, each reticulated element has a plurality of web members thatdefine a plurality of flow passageways through the reticulated element.A process stream contacted with the plurality of reticulated elements istherefore subdivided into a plurality of smaller fluid streams bypassing the process stream through the plurality of flow passagewaysdefined by the web members of each reticulated element. The flows of theprocess stream through the flow passageways within the reticulatedelements and through the void spaces between the reticulated elementswhen multiple reticulated elements are used provides for effective flowdistribution perpendicular to the flow of the process stream through theprocess unit. This method can be applied to process streams that areentering the process unit, at any location within the process unit, atthe exit from the process unit or any combination of these locations.This method can be applied to process streams while concurrentlyproviding for filtration of contaminants from the process stream. Thismethod can be applied to process streams while concurrently performingcatalytic reactions to partially or totally remove or convert desiredchemical species in the process stream.

An additional feature of the present invention can include the step ofusing reticulated elements in a variety of shapes. The shapes caninclude substantially spherical shaped balls, monoliths, squares,raschig rings, saddles, hollow cylinders, perforated disks, disks,single sheets, and solid cylinders, among others. Each shape can besized to individual specifications. Sizes for the shapes used caninclude substantially spherical balls of about ⅛ to 2-inch diameters;monoliths with widths of about ⅛ to 2-inches and lengths of about ⅛ to2-inches; squares with widths of about ⅛ to 2-inches and lengths ofabout ⅛ to 2-inches; raschig rings with inside diameters of about ⅛ to 1inch and outside diameters of about ¼ to 11/2 inches, and heights ofabout ¼ to 2 inches; saddle shapes with radii of about ¼ to 2 inches;hollow cylinders having inside diameters of about ⅛ to 11/4 inches,outside diameters of about ¼ to 2 inches, and heights of about ¼ to 3inches; and solid cylinders having diameters of about ⅛ to 1 inch andheights of about ¼ to 2 inches. Custom-made one-piece disks or singlesheet construction can be custom-fit to the physical configuration of areactor. A further feature of this aspect of the present invention isthat the reticulated elements can be formed in either a disk or singlesheet, each optionally having perforations. An additional feature of thepresent invention is that the reticulated elements when constructed canbe formed into a plurality of segments in order to form an assembledsheet or disk that is custom-fit to the reactor's physicalconfiguration.

An additional feature of the present invention can include the step ofusing reticulated elements in a variety of porosities and pore sizes.The reticulated elements can be manufactured such that they have aporosity of so many pores per inch (“ppi”). For example, this means thata reticulated element of 30 ppi will, when examined by one skilled inthe art, have on average 30 pores per inch. Given that there are about25 millimeters per inch, the pore sizes of such a material would be justunder one millimeter. Pore size in this context is the general size ofthe cavity of the pore recognizing that pores are not perfect spheres.Another important element of pore size is the size of the window openinginto the pore. It is this measure that determines the size of thelargest particle that is trapped or filtered within the pore. Theporosity range of the reticulated elements of the present invention isfrom about 4 to about 800 ppi. This enables customization of the sizeand shape of the reticulated elements for the application constraintsincluding particulate loading and pressure drop constraints. The poresof the reticulated elements can be in a range of about 6 millimeters toabout 100 microns, each being defined by a plurality of web membersforming a plurality of flow passageways through the reticulatedelements. The surface area of these materials can vary even if the ppivalue remains constant.

An additional feature of the present invention can include the step ofusing reticulated elements with different pore sizes in the same processunit so as to remove contaminant materials of a broad range of sizes.The materials of the present invention can filter contaminants down toabout 1 micron in size. Commercially available retention materials arecapable of trapping particles down to about 50 micron in size.

Another feature of the present invention advantageously providesproviding a plurality of reticulated elements over an entire length of aprocess unit. The plurality of reticulated elements can be commingledthroughout the process unit with a catalyst, with multiple catalysts orwith other materials, such as structured packing materials and the like.

In accordance with another aspect of the present invention, the step ofcontacting the contaminated process stream with the reticulated elementsmay include depositing a catalyst on the reticulated elements prior tocontacting the contaminated process stream. Another feature of thisaspect of the present invention may include the use of reticulatedelements as a substrate having a substantially uniform coating of aselected catalyst including a porous alumina coating with a Group VI-Bmetal or a Group VIII metal, or both. Preferably, the Group VI-B metalis molybdenum and preferably, the Group VIII metal is either nickel orcobalt. More preferably, the Group VI-B metal and Group VIII metal areimpregnated into the reticulated elements. The method of the presentinvention is useful to extend the run life of the catalyst bed. Thecatalytically active reticulated elements can be utilized to reactdiolefins or other polymer precursors and also to act as a filter and asa flow distributor. By filtering solids and partially reacting anypolymer precursors, e.g., diolefins, fouling of the catalyst is reducedeffectively extending the run time of the reactor.

In accordance with another aspect of the present invention, thefiltration method may include the step of filtering solid particulatematerial or sediments that form within a process unit in order to reducefouling or plugging of downstream equipment. This aspect of the presentinvention may include the steps of providing one or more reticulatedelements; contacting a process stream containing the particulatematerial or sediments with the reticulated elements; removing theparticulate material or sediments from the process stream; and providinga relatively particulate material or sediments-free process stream forfurther processing. The reticulated elements can be located at one ormore locations within the process unit or at the outlet of the processunit or a combination of both. This method of removing sediments canalso be used in distillation columns to provide a relatively sedimentfree process stream for further processing. The method of the presentinvention for filtering process streams in catalytic bed process units,when compared with prior art methods, has the advantages of reducing thevolume of retention materials required; lowering capital costs;improving the filtration of the solid particular matter from the feedstreams; decreasing the pressure drop across the system; increasing runtime of the reactor; allowing for the use of catalysts that have higheractivity, lowering operating costs; increasing process safety; andreducing environmental concerns.

In accordance with another aspect of the invention, the foregoingadvantages have also been achieved through the present apparatus andmethod for separating at least one process stream into one or morecomponent process streams having desired compositions using CELLDISTmaterials in a component separation unit.

The method may include the steps of providing CELLDIST materials in thecomponent separation unit, positioning the CELLDIST materials within atleast one zone of the component separation unit (hereinafter referred toas the “unit”), introducing two or more phases of the process streaminto the zone containing the CELLDIST materials, contacting the two ormore phases at or near the surface of the CELLDIST materials tofacilitate mass transfer and recovering at least a portion of one ormore of the phases from the unit as one or more component processstreams, wherein the component process streams have a desiredcomposition.

A feature of the present invention is that the phases have desiredcompositions upon exiting the zone of CELLDIST material. One or morecomponent process streams can be recovered from one or more locationsbetween the top of the unit and the bottom of the unit. In oneembodiment, the surface of the CELLDIST material can have a surface areaof up to about 4000 square meters per cubic meter of CELLDIST materialin the unit. Preferably, the surface of the CELLDIST material has asurface area in the range of about 250-4000 square meters per cubicmeter of CELLDIST material in the unit.

In one aspect, the solid component of the CELLDIST materials in the unitcan be selected from the group consisting of oxides, carbides, nitrides,borides, a ceramic material, a metallic material, a polymeric materialand a chemical vapor deposition material or combinations thereof.CELLDIST material can also be formed from a corrosion resistant materialor predominantly from silicon carbide.

A feature of the present invention is that the component separation unitcan include both CELLDIST materials and one or more conventional unitinternals. The process streams entering the unit may be vapor steams,liquid streams or a combination of both. One or more phases containedwithin the unit can be passed through one or more zones of CELLDISTmaterial installed within the unit.

In accordance with another aspect of the present invention, a method ofaltering the composition of at least one process stream in a componentseparation unit can include positioning at least one bed of CELLDISTmaterial within a unit, creating two or more desired phases from the atleast one process stream, passing the two or more phases through the atleast one bed of CELLDIST material, whereby the composition of the twoor more phases is changed as it passes through the CELLDIST material,thereby producing at least one component process stream with a desiredcomposition, and recovering the at least one component process streamfrom the unit. A feature of the invention is that one or more componentprocess streams are recovered from locations between the top of the unitand the bottom of the unit. In one aspect, the bed or beds of CELLDISTmaterial are custom fit to the cross sectional configuration of theunit. In another aspect, the bed or beds of CELLDIST material iscomprised of a plurality of randomly packed elements.

In accordance with another aspect of the present invention, a method ofaltering the composition of at least one process stream via distillationin a distillation unit can include positioning at least one bed ofCELLDIST material within a distillation unit, creating desired phasesfrom the at least one process stream, passing the phases through the atleast one bed of CELLDIST material, whereby the composition of thephases is changed as it passes through the CELLDIST material, therebyproducing at least one component process stream with a desiredcomposition, and recovering the at least one component process streamfrom the distillation unit. A feature of the invention is that one ormore component process streams are recovered from locations between thetop of the distillation unit and the bottom of the distillation unit. Inone aspect, the bed or beds of CELLDIST material are custom fit to thecross sectional configuration of the distillation unit. In anotheraspect, the bed or beds of CELLDIST material is comprised of a pluralityof randomly packed CELLDIST elements.

In accordance with another aspect of the present invention, a method ofaltering the composition of at least one process stream via absorptionin an absorber can include positioning at least one bed of CELLDISTmaterial within an absorber, creating two or more desired phases fromthe at least one process stream, passing the two or more phases throughthe at least one bed of CELLDIST material, whereby the composition ofthe two or more phases is changed as they pass through the CELLDISTmaterial, thereby producing at least one component process stream with adesired composition, and recovering the at least one component processstream from the absorber. A feature of the invention is that one or morecomponent process streams are recovered from locations between the topof the absorber and the bottom of the absorber. In one aspect, the bedor beds of CELLDIST material are custom fit to the cross sectionalconfiguration of the absorber. In another aspect, the bed or beds ofCELLDIST material is comprised of a plurality of randomly packedCELLDIST elements.

In accordance with another aspect of the present invention, a method ofaltering the composition of at least one process stream via extractionin an extractor can include positioning at least one bed of CELLDISTmaterial within a extractor, creating desired phases from the at leastone process stream, passing the phases through the at least one bed ofCELLDIST material, whereby the composition of the phases is changed asit passes through the CELLDIST material, thereby producing at least onecomponent process stream with a desired composition, and recovering theat least one component process stream from the extractor. A feature ofthe invention is that one or more component process streams arerecovered from locations between the top of the extractor and the bottomof the extractor. In one aspect, the bed or beds of CELLDIST materialare custom fit to the cross sectional configuration of the extractor. Inanother aspect, the bed or beds of CELLDIST material is comprised of aplurality of randomly packed CELLDIST elements.

Another aspect of the present invention involves facilitating theseparation of process streams into component process steams via masstransfer in a component separation unit. The unit preferably has one ormore beds of CELLDIST material. Such one or more beds can be composed ofa plurality of randomly packed CELLDIST material or CELLDIST materialthat is custom fit to the unit's cross sectional configuration or acombination thereof. The depths of the one or more beds is set so as toprovide the required number of theoretical stages to achieve the desiredseparation of some or all of one or more of the species in the processstreams.

In yet another aspect, the present invention relates to a componentseparation unit assembly with at least one CELLDIST material disposedtherein, wherein the amount of at least one CELLDIST material in theunit preferably is sufficient to provide the number of theoreticalstages required to separate one or more process streams into componentprocess streams containing desired compositions of certain of thespecies in the one or more process streams.

The methods and assemblies of the present invention for separating oneor more process streams into component process streams having desiredcompositions using CELLDIST materials in a component separation unit,when compared with prior art methods, have the advantages, among others,of reducing the complexity and cost of designing, fabricating,installing, operating and maintaining units and of providing moreefficient contacting of process streams to achieve the desiredseparation.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a partial cross-sectional side view of a single fixedcatalytic bed process unit showing a specific embodiment of the presentinvention;

FIG. 2 is a partial cross-sectional side view of a multiple fixed bedchemical reactor showing another embodiment of the present invention;

FIG. 3 is a partial cross sectional side view of a combustor-styleregenerator fluidized bed reactor showing an embodiment of the presentinvention;

FIG. 4 is a partial cross-sectional side view of a two-stage regeneratorfluidized bed reactor showing an embodiment of the present invention;

FIG. 5 is a partial cross-sectional side view of a radial flow reactorshowing another embodiment of the present invention;

FIG. 6 is a perspective view of a perforated disk made of reticulatedmaterial in accordance with the present invention;

FIG. 7 is a perspective view of a saddle made of reticulated material inaccordance with the present invention;

FIG. 8 is a perspective view of a hollow cylinder made of reticulatedmaterial in accordance with the present invention;

FIG. 9 is a perspective view of an example of a one-piece sheet made ofreticulated material in accordance with the present invention;

FIG. 10 is a perspective view of an assembled disk made of reticulatedmaterial in accordance with the present invention;

FIG. 11 is a perspective view of balls made of reticulated material inaccordance with the present invention;

FIG. 12 is a perspective view of a solid cylinder made of reticulatedmaterial in accordance with the present invention;

FIG. 13 is a perspective view of a hollow cylinder made of reticulatedmaterial in accordance with the present invention;

FIG. 14 is a perspective view of a monolith made of reticulated materialin accordance with the present invention;

FIG. 15 is a partial cross-sectional side view of a distillation columnshowing an embodiment of the present invention;

FIG. 16 is a perspective view of a layer of reticulated elements with avoid space between each reticulated element that is varied in accordancewith the present invention;

FIG. 17 is a graph comparing the pressure drop in distillatehydrotreaters with the reticulated elements of the present inventioninstalled to the pressure drop in a distillate hydrotreaters with priorart, retention materials installed;

FIG. 18 is a graph illustrative of the effect of the present inventionon the pressure drop in naphtha hydrotreater units;

FIG. 19 is a partial cross-sectional side view of a down-flow processunit with multiple layers of reticulated elements to provide the methodsof the present invention at the entrance of the process unit, at twoother locations within the process unit and at the outlet of the processunit in accordance with an embodiment of the present invention;

FIG. 20 is a partial cross-sectional view of a process unit with layersof reticulated elements of differing porosities to enable filtering ofcontaminants with a wide range of particle sizes in accordance with anembodiment of the present invention;

FIG. 21 is a perspective view of a top and a bottom of a piece of areticulated element on which had been dripped water tinted with foodcoloring illustrating the perpendicular flow distribution of thereticulated elements in accordance with the present invention;

FIG. 22 is a perspective view of a process unit with the reticulatedelements of the present invention randomly packed throughout an entirelength of a catalyst bed according to an embodiment of the presentinvention;

FIG. 23 is a partial cross-sectional side view of a conventionalcomponent separation unit in accordance with the prior art;

FIG. 24 is a partial cross-sectional side view of a component separationunit containing CELLDIST material, conventional trays and conventionaldistributors according to the present invention;

FIG. 25 is a partial cross-sectional side view of a component separationunit utilizing conventional packing material and conventionaldistributors to achieve separation of process streams into componentprocess streams in accordance with the prior art;

FIG. 26 is a partial cross-sectional side view of a component separationunit utilizing CELLDIST material, conventional packing material andconventional distributors to achieve separation of process streams intocomponent process streams in accordance with an embodiment of thepresent invention;

FIG. 27 is a perspective view of an example of a one-piece sheet made ofCELLDIST material for use in a component separation unit in accordancewith the present invention; and

FIG. 28 is a perspective view of an assembled disk made of CELLDISTmaterial for use in a component separation unit in accordance with thepresent invention.

While the invention will be described in connection with the preferredembodiment, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications, and equivalents, as may be includedwithin the spirit and the scope of the invention as defined by theappended claims.

DETAILED DESCRIPTION AND SPECIFIC EMBODIMENTS

With reference to FIG. 1, for treatment of a process stream a singlefixed catalytic bed process unit 22 with reticulated elements 15 in theshape of substantially spherical balls 122 (FIG. 11) will be described,although as previously discussed other shapes of the reticulatedelements 15 may be used, as well as other process units. If the processunit 22 is of a down flow configuration, the contaminated process stream20 will enter the process unit 22 at the inlet 24. The invention may beused in either fixed or fluidized catalytic bed process units.Preferably, the present invention is used in one or more fixed beds, ineither an up flow or down flow or radial flow configuration. Preferably,the catalytic bed process units include hydrotreater, hydrorefiner,hydrocracker, reformer, alkylation, dealkylation, isomerization,esterification, and polymerization reactors. Contaminants typicallyfound in the feed stream include dirt, iron oxide, iron sulfide,asphaltenes, coke fines, soot, catalyst fines, sediments or otherentrained foreign particulate matter, salts in distillation columns,particulates in gas streams, sulfur or sulfides from tail gas units, orpolymer precursors such as diolefins. A layer 26, preferably layers 26,28, of reticulated elements 15 is provided in the vessel in an amountsufficient to filter the contaminants from the process stream 20 for aslong as desired including, but not limited to, as long as the catalystwithin the reactor is sufficiently active to justify operation of thereactor. Preferably, multiple layers 26, 28 can be provided wherein thesize of the reticulated elements 15 such as balls 122 is graduated fromone size in layer 26 to another size in layer 28 as the incoming processstream flows through the bed of reticulated elements 15. Reticulatedelements can include foam materials and monolith materials. Foammaterials generally have a random pattern, while the monoliths have amore uniform pattern. If a reticulated ceramic element is used, thereticulated ceramic elements can be made from any commercially availablematerials, for example, zirconia toughened alumina, commonly referred toas ZTA. ZTA is available from Fiber Ceramics, Inc. headquartered inCudahy, Wis. An exemplary monolith for use in the present invention isavailable from Corning, Inc. headquartered in Corning, N.Y. Thegraduated sizing of the reticulated elements 15 allows the filtering ofa broad range of sizes of contaminants.

The present invention advantageously provides a method of removingcontaminants from a contaminated process stream. The method preferablyis performed by providing reticulated elements preferably randomlypacked with a void space between each reticulated element to enhancefiltration of contaminants in such a way that the decontaminated processstream may pass through the reticulated material unimpeded. The presentinvention provides a method whereby the entirety of the reticulatedelements can be utilized to filter contaminants from the process stream.In catalytic bed process units, the reticulated elements can be sizedsuch that the catalyst bed has exhausted its catalytic activity beforethe reticulated elements have exhausted their ability to filter outcontaminant particles. This method enables use of the entire bed ofreticulated elements, as opposed to current methods that eventually clogthe top six to twelve inches of the retention materials conventionallyavailable. With such materials, beds deeper than about one foot areessentially of no use in removing particulate contaminants from processstreams. Further, with such materials, once the top of the bed isplugged, the pressure drop in the equipment begins to escalate,requiring a shutdown to remove and replace the clogged materials fromthe process unit.

Data has been collected from different process units that haveexperimented with the reticulated elements of the present invention. Thereticulated elements of the current invention have performeddramatically better than conventional retention materials availablecommercially.

Example 1 Use in a Distillate Hydrotreater

Data were obtained from a refinery for four distillate hydrotreaters invirtually identical process conditions. Two of the hydrotreaters, A andB, contained conventional reticulated materials, known as “ring gradingsystems.” The remaining two hydrotreaters, C and D, used the reticulatedelements of the present invention. FIG. 17 shows a comparison of thepressure drop of the four hydrotreaters using conventional ring gradingsystems and the reticulated elements of the present invention. As can beseen in the graph, the pressure drop remained low relative tostart-of-run pressure drop over a period in excess of 450 days in the Cand D hydrotreaters containing the reticulated elements, while the A andB hydrotreaters using the conventional ring grading system showed adramatic pressure increase after only 200 days in service. The resultsof the pressure drop comparison can be seen in Table 1. The contaminatedprocess streams in the distillate hydrotreaters were predominantly in aliquid phase. In the C hydrotreater, the differential pressure was only8 psi at 450 days. In the D hydrotreater, the differential pressure wasonly 0.5 psi at 450 days. The differential pressure for the A and Bhydrotreaters was 82.5 psi and 54 psi respectively. In comparison, the Cand D hydrotreaters with the reticulated elements of the presentinvention performed significantly better than the conventional ringgrading systems. The lower differential pressure associated with thereticulated elements of the present invention allows the time betweenturnarounds to be extended dramatically.

TABLE 1 Pressure Drop (“ΔP”) in Example 1-Distillate HydrotreatersInitial ΔP ΔP at ΔP at % Change from 0 Hydrotreater at 0 day 200 days450 days days to 450 days A 17.5 38 100 470% increase B 21 38 75 257%increase C 30 30 38  27% increase D 39 40.5 39.5  1.3% increase 

A typical pressure drop scenario is to have a low pressure drop for thefirst months of operation, but then, at a time that is not predictable,the pressure increases significantly over a relatively short period to apoint where the unit must be shutdown to remove the pluggage, replacethe removed material and restart the unit. This can be problematic giventhe unpredictability of the event, the need to acquire replacementmaterials with very short lead-time or to maintain sufficient extrainventory of replacement materials or to extend the down-time to awaitdelivery of replacement materials. With use of the reticulated elementsin accordance with the methods described herein, the pressure dropremains low for a predictable period of time based on the level ofcontaminants in the process stream and the capacity of the reticulatedelements loaded in the process unit. Sufficient reticulated elements maybe loaded such that the catalyst in the unit is exhausted before thereticulated elements are saturated.

Example 2 Use in a Naphtha Hydrotreater

Data was obtained from a refinery with four naphtha hydrotreaters. Threeof the hydrotreaters (A, B, and C) used conventional ring gradingsystems, while the remaining hydrotreater (D) used the reticulatedelements of the present invention. FIG. 18 illustrates that comparativepressure drop between the four hydrotreaters. At the end of 200 days,the unit with the reticulated elements D experienced minimal pressuredrop, i.e. −4 psi for hydrotreater D, compared to the pressure dropexperienced by the three units containing ring grading systems, i.e. 10psi for hydrotreater B and 22 psi for hydrotreater C. The contaminatedprocess streams in the naphtha hydrotreaters were predominantly in avapor phase. The reticulated elements of the present invention filteredefficiently and effectively while the conventional ring grading systemsbecame clogged.

Referring again to FIG. 1, unless otherwise noted, in addition tofiltering the contaminated process stream 20, the reticulated material15 may also enable a uniform distribution and flow of the incomingprocess stream 20 to the catalyst bed 32.

By passing the process stream through a plurality of flow passageways120 (FIG. 9) defined by web members 123 (FIG. 9) of the reticulatedmaterial 15 in layers 26, 28, the incoming process stream 20 may also bedistributed by subdividing the incoming process stream into a pluralityof smaller fluid streams and then resubdividing, a plurality of times,the smaller streams so that the incoming process stream is spreaduniformly across the fluid entry cross-section 34, taken along line34-34, of the catalyst bed 32. The process stream 20 is reacted in thecatalyst bed 32. Preferably the catalyst bed 32 contains discrete solidcatalyst particles 36.

For catalytic bed process units, methods of the present invention filterparticulate contaminants before they reach the catalytic bed. Thisallows for increased efficiency of the catalyst bed since more of thesurface area of the catalyst is available for use as a catalyst whencompared to systems with conventional retention materials, such as thering grading systems used in Examples 1 and 2. As a result, smallersized, more catalytically active catalyst elements can be used due tothe lower average pressure drop of the unit resulting in a gain incatalyst activity of about 10%-15%.

The reticulated material 15 may be used to filter and retainparticulates 36 from the outgoing process stream 38. Small particulatematerial 36 that may be entrained in the outlet process stream may befiltered, or captured, from the process stream 38 and retained byreticulated material layers 40, 42. Preferably, the size of thereticulated material in layers 40, 42 is graduated from a size in layer40 to another size in layer 42 at the outlet 44 of the reactor 22. Inaddition, sediments of material may form in the process unit, e.g.,sediments formed by excessive hydrocracking of residual oils that mayplug or foul downstream equipment. These sediments may be filtered fromthe outgoing process stream 38 by the reticulated material 15.Preferably, the size of the reticulated material in layers 40, 42 isgraduated from a size in layer 40 to another size in layer 42 at theoutlet 44 of the reactor 22. Alternately, the invention may also be usedin an up flow configuration wherein the contaminated process stream 46would instead enter the unit at 44 at the lower end 39 and the outletprocess stream 25 would exit the process unit at 24 at the upper end 47of reactor 22.

As previously discussed, another advantage of the present invention isto react activated or partially activated reticulated material 15 withpolymer precursors in a contaminated process stream 20. Condensationpolymerization of diolefins may occur in the process unit 32 after thecontaminated process stream 20 is heated, generally prior tointroduction into the process unit 22, thereby forming foulants in theprocess unit 32 itself that may gum or plug the process unit 32. As thefoulants form in the process unit, they cannot be filtered from thecontaminated process stream 20 before flowing across the fluid entrycross-section 34. Therefore, the layer or layers 26, 28, 40, 42 ofreticulated material 15 may be coated with an alumina powder that mayalso act as a substrate for catalyst materials to form partiallyactivated reticulated material. As used herein, an “activated support”means (1) a reticulated material that has been impregnated with catalystmaterials or (2) a reticulated material that may be an oxide, nitride,or carbide of a metal or (3) a reticulated material that containszeolite or inorganic oxides, e.g., alumina, silica, silica-alumina,magnesia, silica-magnesia or titania. As used herein, a “partiallyactivated support” means an activated support material that has beenpurposefully made less active or partially deactivated in order toachieve a slower reaction rate or to partially react the materialscontacted.

With regard to contaminated process streams, coated reticulated material15 may also be used, wherein the coating may comprise one of severalconventional catalysts. Alumina may be used as an active coating,optionally but preferably, alumina may be used as a support tostrengthen the catalyst. The catalyst according to this inventionpreferably comprises a metal of Group VI-B or a member of Group VIII, orboth, impregnated into an alumina based support. Accordingly, thecatalyst may comprise at least one of chromium, molybdenum and tungstenin combination with at least one of iron, nickel, cobalt, platinum,palladium and iridium. The use of palladium is particularly useful inthe removal of acetylene and diolefins from ethylene, the removal ofoxygen, the removal of hydrogen. Of the Group VI-B metals, molybdenum ismost preferred. The catalyst preferably will contain from about 2% toabout 14% by weight of Group VI-B metal. Of the Group VIII metals,nickel and cobalt are most preferred. The amount of Group VIII metal inthe catalyst is preferably from about 0.5% to about 10% by weight.

With reference to FIG. 2, a multiple fixed catalyst bed process unit 46having two fixed catalyst beds 48, 50 with reticulated material 15 inthe shape of saddles 126 (FIG. 7) will be described. The reactor 46 isillustrated in a down flow configuration, wherein the contaminatedprocess stream 51 will enter the unit 46 at the inlet 52 and the outletprocess stream 54 will exit the unit at the outlets 56, 60. A partiallyreacted process stream 58 may be accumulated at the outlet 61 of thefirst fixed bed 48 and withdrawn at the collector tray 60. The partiallyreacted process stream 58 may be heated or quenched or otherwise treatedbefore reintroduction into the reactor 46 as a partially reacted processstream 62 at the mixing chamber 64. The partially reacted process stream58 may be removed for redistribution, heating, or other processing stepsas required before reintroducing the partially reacted process stream 62into the reactor 46 for reaction with a succeeding catalyst bed 50. Anadditional layer 70 of reticulated material 15 may be provided forfiltration and distribution to remove any contaminants entrained from orformed by the processing equipment used in the additional processingsteps such as dirt, iron oxide, iron sulfide, asphaltenes, coke fines,soot, catalyst fines, sediments or other entrained foreign particulatematter, salts in distillation columns, particulates in gas streams,sulfur or sulfides from tail gas units, or polymer precursors such asdiolefins.

Layers 66, 68, 70 of reticulated material 15 are provided in the reactor46 below the inlet 52 and mixing chamber 64 in an amount sufficient tofilter the process stream 51 and the partially reacted process stream62. Preferably, the multiple layers 66, 68, 70 are provided such thatthe porosity of the reticulated material 15 is graduated from a porosityin layer 66 to another porosity in layer 68 to another porosity in layer70 as the incoming contaminated process stream flows through thereticulated material 15. Optionally, the present invention may bepracticed with or without conventional basket screens 72. Preferably,the fixed catalyst beds 48, 50 contain discrete solid catalyst particles74.

Another feature of the present invention advantageously providesproviding a plurality of reticulated elements 15 over an entire lengthof a process unit. The plurality of reticulated elements 15 can becommingled throughout the process unit with a catalyst 19, as shown inFIG. 22.

As previously discussed, an advantage of the present invention is thatit may also be used to distribute the process stream. The process stream51 may also be distributed while being filtered by subdividing theincoming process stream into a plurality of smaller fluid streams bypassing the process stream through a plurality of flow passageways 120(FIG. 9) defined by the web members 123 (FIG. 9) of the reticulatedmaterial 15; then resubdividing, a plurality of times, the smallerstreams so that the incoming process stream is spread uniformly acrossthe fluid entry cross-section of the catalyst bed 76. The feed 51 isthen reacted in the catalyst bed 48, before being withdrawn as apartially reacted process stream 58 at the collector plate 60. Themethod of filtration and distribution is then repeated for the partiallyreacted process stream 62 as it flows into the mixing chamber 64 andpasses through the reticulated material layer 70.

Another feature of the present invention is that the reticulatedmaterial 15 may also be used to capture and retain catalyst particles 74from the outflowing partially reacted process stream 58 and the reactedprocess stream 54. The reticulated material 126 in layers 78, 80 at theoutlet 61 of the first fixed bed 48 and the reticulated material 126 inlayers 82, 84 at the outlet 56 of the second fixed bed 50 are used tofilter and retain catalyst particles 74 that may be entrained in thepartially reacted process stream 58 or reacted process stream 54. Asdiscussed with reference to FIG. 1, for capturing and retaining catalyst74 from a partially reacted or a reacted outflowing process stream ineither a single or a multiple fixed bed chemical reactor, thereticulated material 15 is preferably graduated from a porosity toanother porosity as shown in FIG. 2 for layers 78, 80 and 82, 84,respectively for each bed 48, 50. Optionally, the porosity of thereticulated material may also be graduated from small pores to largepores. Alternatively, the porosity of the reticulated material may beinversely graduated from large pores to small pores to filter sedimentsthat may form in the catalyst bed.

A further advantage of the present invention is that the reticulatedmaterial 15 may be activated or impregnated with catalytically activematerial to react with polymer precursors in process streams 51, 62. Asdepicted in FIG. 2, layers 66, 68, 70 of reticulated material 15 maycontain an activated support including inorganic oxides preferablyselected from the group consisting of alumina, silica, silica-alumina,magnesia, silica-magnesia or titania or zeolites preferably selectedfrom the group consisting of zeolite L, zeolite X, and zeolite Y, whichmay be added to the reticulated material as a substrate for catalystmaterials. Optionally, the reticulated material may be impregnated withcatalyst materials or the reticulated material may be an oxide, nitride,carbide or boride of a metal as disclosed in U.S. Pat. No. 5,399,535,which is hereby incorporated by reference to the extent it is notinconsistent with the present invention.

Activated or partially activated reticulated material as described abovemay be used to control the hydrogenation rate of the diolefins or otherpolymer precursors to prevent fouling or gum formation. When endothermicreactions require the addition of heat to the partially reacted processstream 58, preferably the reticulated material 15 of layer 70 is alsoactivated or partially activated. The invention may also be practicedwith coated reticulated material, wherein the coating may comprise oneof several conventional catalysts. Alumina may be used on an activecoating or support. The catalyst according to this invention preferablycomprises a metal of Group VI-B or a member of Group VIII, or both,impregnated into the reticulated material, inorganic oxide or zeolite.Accordingly, the catalyst may comprise at least one of chromium,molybdenum and tungsten in combination with at least one of iron,nickel, cobalt, platinum, palladium and iridium. Of the Group VI-Bmetals, molybdenum is most preferred. The catalyst preferably willcontain from about 2% to about 14% by weight of Group VI-B metal. Of theGroup VIII metals, nickel and cobalt are most preferred. The amount ofGroup VIII metal in the catalyst is preferably from about 0.5% to about10% by weight.

FIG. 3 illustrates a conventional combustor-style fluidized bed reactor88, 90. Layers 86, 92 of reticulated material 15 may be used influidized bed chemical reactors 90 and in a combustor, or regenerator88, to reduce entrance losses and maldistribution of the vapor or airflows. The inlet air 93 to the combustor or regenerator 88 is flowedthrough the reticulated material layer 86 to subdivide the stream into aplurality of smaller flowing streams. The reticulated material 15 may bea single circular disk 124 (FIG. 6) without the illustrated perforation125; however it may be an oval or square sheet 121 (FIG. 9), or anygeometric configuration desired including an assembled disk 134 (FIG.10). Optionally, multiple disks 86, 92 (FIG. 3) may be used. Also, thedisk 124 (FIG. 7) or sheet 121 (FIG. 9) may optionally containperforations. The subdivision of the vapor or air flows may reduce theturbulence of the incoming vapor or air streams, thus reducing thecompressor horsepower usage or allowing for an increase in flow rate,depending on the process constraints of the particular combustor-stylefluidized bed reactor (FIG. 3). A further advantage of the presentinvention is that the subdivided vapor or air flows may more uniformlydistribute the vapor or air 94 throughout the combustor or regenerator88. In addition, another layer 92 of reticulated material 15 may be usedto uniformly distribute any fluffing vapors 96 used in the fluidized bedreactor 90.

Alternatively, in FIG. 4, which depicts a conventional two-stageregenerator fluidized bed reactor 104, layers 98, 112 of the reticulatedmaterial 15 may be used similarly as discussed in FIG. 3 for asingle-stage combustor or regenerator. The turbulent inlet air 102 tothe combustor or regenerator first stage 108 is flowed through the layer98 of reticulated material 15 to subdivide the stream, preferably into aplurality of smaller flowing streams. Preferably, the reticulatedmaterial 15 is a single circular disk 124 (FIG. 6) without theperforations 125; however it may be an oval or square sheet 121 (FIG.9), or any geometric configuration desired including an assembled disk134 (FIG. 10). Optionally, multiple disks 98, 112 (FIG. 4) may be used.Also, the disk 124 (FIG. 7) or sheet 121 (FIG. 9) may optionally containperforations. Similarly, for the second-stage 110, the turbulent inletair 106 may be flowed through the layer 100 of reticulated material 15to subdivide the stream into a plurality of smaller flowing streams. Thesubdivision of the vapor or air flows may reduce the turbulence of theincoming vapor or air streams, thus reducing the compressor horsepowerusage or allowing for an increase in flow rate, depending on the processconstraints of the two-stage regenerator fluidized bed reactor 104, 116.A further advantage of the present invention is that the subdividedvapor or air flows may more uniformly distribute the vapor or airthroughout the combustor or regenerator chambers 108, 110. In addition,another layer of reticulated elements 112 may be used to uniformlydistribute any fluffing vapors 114 used in the fluidized bed reactor116.

With reference to FIG. 5, for treatment of a contaminated process streamin vapor form, a radial flow fixed bed chemical reactor 94 withreticulated material 15 in the shape of substantially spherical balls122 (FIG. 11) is illustrated, although, as previously discussed, othershapes may be used. The contaminated process stream in vapor form 92will enter the radial flow reactor 94 at the inlet 96. A layer 98 ofreticulated material 15, more preferably layers 98, 100 of reticulatedmaterial 15, is provided in the vessel between the deflection baffle 122and the scallop 104. The layers of 98, 100 reticulated material 15 aidin filtering contaminants such as dirt, iron oxide, iron sulfide,asphaltenes, coke fines, soot, catalyst fines, sediments or otherentrained foreign particulate matter, or polymer precursors such asdiolefins entrained in the contaminated vapor feed 92 before reaction inthe fixed catalyst bed 108 and discharge through the center pipe 110 asthe reacted process stream 112. Also as previously discussed, anadvantage of the present invention is that the reticulated material 15may be used to capture and retain catalyst from outlet streams, shownhere in the unloading tubes 106.

The reticulated elements can be used to filter contaminants, such assediments, in other types of process equipment. FIG. 15 illustratesanother embodiment of the present invention. In this embodiment,reticulated elements 95 are used for removing sediments, such as salts,in a distillation column 90. The method of filtering sediments formed inprocess equipment preferably includes providing a layer of reticulatedelements packed with a void space between each reticulated element. Thevoid space is varied to enhance filtration of smaller contaminants on asurface of the reticulated elements while allowing larger contaminantsto pass through to prevent pluggage of the layer of reticulatedelements. The method further provides for contacting a process streamcontaining the sediments with the reticulated elements thereby removingthe sediments from the process stream by removing the smallercontaminants on the surface of the reticulated elements and allowing thelarger contaminants to proceed through the void spaces between eachreticulated element. This method produces a relatively sediment-freeprocess stream for further processing.

FIG. 6 illustrates a specific embodiment of the present invention as areticulated elements disk 124. Optionally, the disks may haveperforations 125. Preferably, multiple perforations are used toaccommodate screen baskets that may optionally be filled withreticulated elements. Other shapes may include saddles 126 (FIG. 7),hollow cylinders 128 (FIG. 8), single sheets 121 of reticulated material15 (FIG. 9), disks 134 formed from a plurality of segments 134 a-f (FIG.10), substantially spherical balls 122 (FIG. 11), solid cylinders 132(FIG. 12), raschig rings 130 (FIG. 13), squares (FIG. 14), and monoliths(FIG. 14). Each shape may be sized to individual specifications. Sizesfor the shapes used may include substantially spherical balls of about ⅛to 2 inch diameters; raschig rings with inside diameters of about ⅛ to 1inch and outside diameters of about ¼ to 11/2 inches and heights ofabout ¼ to 2 inches; saddle shapes with radii of about ¼ to 2 inches;hollow cylinders having inside diameters of about ⅛ to 11/4 inches,outside diameters of about ¼ to 2 inches, and heights of about ¼ to 3inches; and solid cylinders having diameters of about ⅛ to 1 inch andheights of about ¼ to 2 inches. Custom-made one-piece disks 124 orsingle sheet 121 construction may be custom-fit to the physicalconfiguration of a reactor. A further feature of this aspect of thepresent invention is that the reticulated material 15 may be formed ineither a disk 124 or single sheet 121 having perforations 125. Anadditional feature of the present invention is that the reticulatedelements when constructed may be formed into a plurality of segments inorder to form an assembled sheet or disk that is custom-fit to thereactor's physical configuration. Porosities of the reticulated elementsmay range from 4 to 800 ppi. Preferably, for filtration the porosity mayrange from about 4 to 80 ppi. More preferably, for filtration theporosity may range from about 10 to 65 ppi. This enables customizationof the size and shape of the reticulated material 15 for theapplication, size, particulate loading and pressure drop constraints.The reticulate element material surrounding the pores, or openings, ofthe reticulated elements form the web members 123 (FIG. 9), which inturn define the flow passageways 120 (FIG. 9).

The present invention also advantageously provides a method ofperpendicular flow distribution in process units. This perpendicularflow distribution method includes providing one or more reticulatedelements in the process unit. When only one reticulated element is used,it is typically large enough to effectively span the process unit. Whenmultiple reticulated elements are used, they are typically arranged in arandomly packed bed. Regardless of the configuration of the reticulatedelements, each reticulated element has a plurality of web members thatdefine a plurality of flow passageways through the reticulated element.A process stream contacted with the plurality of reticulated elements istherefore subdivided into a plurality of smaller fluid streams bypassing the process stream through the plurality of flow passagewaysdefined by the web members of each reticulated element. The flows of theprocess stream through the flow passageways within the reticulatedelements and through the void spaces between the reticulated elementswhen multiple reticulated elements are used provides for effective flowdistribution perpendicular to the flow of the process stream through theprocess unit. This method can be applied to process streams that areentering the process unit, at any location within the process unit, atthe exit from the process unit or any combination of these locations, asillustrated in FIG. 19. This method can be applied to process streamswhile concurrently providing for filtration of contaminants from theprocess stream. This method can be applied to process streams whileconcurrently performing catalytic reactions to partially or totallyremove or convert desired chemical species in the process stream.

FIG. 21 illustrates the amount of perpendicular flow that thereticulated elements of the present invention are capable of producing.An experiment was performed using a dropper with a dropper diameter ofapproximately 1/16”. The reticulated element distributed the liquidperpendicularly to a diameter of about seven times the diameter of thedropper. The flow was not distributed down the reticulated element asmuch. The significant distribution was made in the horizontal plane andnot a vertical plane. When used in process units, the reticulatedelements significantly perpendicularly disperses the fluid to preventchanneling and other problems discussed herein.

An additional feature of the present invention can include the step ofusing reticulated elements in a variety of porosities and pore sizes, asshown in FIG. 20. The reticulated elements can be manufactured such thatthey have a porosity of so many pores per inch (“ppi”). For example,this means that a reticulated element of 30 ppi will, when examined byone skilled in the art, have on average 30 pores per inch. The poresizes of such a material would be about one millimeter. Pore size inthis context is the general size of the cavity of the pore recognizingthat pores are not perfect spheres. Another important element of poresize is the size of the window opening into the pore. It is this measurethat determines the size of the largest particle that can be trapped orfiltered within the pore. The porosity range of the reticulated elementsof the present invention is from about 4 to 800 ppi. This enablescustomization of the size and shape of the reticulated elements for theapplication constraints including particulate loading and pressure dropconstraints. The pores of the reticulated elements can be in a range ofabout 6 millimeters to about 100 microns, each being defined by aplurality of web members forming a plurality of flow passageways throughthe reticulated elements.

As an advantage of the present invention, the filtering method providesfor more efficient filtration within the process unit. Since thecontaminants do not cake up on the first inches of the reticulatedelements, as with conventional retention materials, all of the filterbed can be effectively used. Pressure drop through the reticulatedelements can remain low as long as sufficient reticulated elements areutilized such that the process unit reaches an end-of-run conditionother than pressure drop increase. The lower pressure drop increases thesafety of operating the unit since downstream equipment is not deprivedof flow and the upstream equipment does not pressure up. The run timesbetween catalyst changes are significantly increased since the processequipment can operate much longer than with previous filtration methodsbefore the process equipment end-of-run conditions.

Another advantage of the present invention is that smaller sizedcatalysts can be used in catalyst bed process units since the catalystbed is subjected to a much lower cycle-average pressure drop. The resultof using the smaller, more catalytically reactive catalyst is a gain inactivity of about 10% to about 15%. The entire surface area of thecatalyst can be used for its intended purpose, which is to modify andincrease the rate of a reaction, due to a much lower average pressuredrop per cycle for the process unit.

Another advantage of the present invention is, as depicted in FIG. 21,the use of one or more layers of reticulated elements at variouslocations within a process unit to facilitate perpendicular flowredistribution to mitigate channeling and other symptoms of flowmaldistribution. Such one or more layers of reticulated elements withina process unit also facilitate filtration of particulate contaminantswithin the process unit.

With reference to FIG. 23, shown is a prior art distillation column withconventional trays 12 and two conventional distributors 11, one locatednear the top and one near the bottom of the unit. Process streamsentering the unit include the inlet process stream 151, a portion of theoverhead liquid stream 152 exiting the condenser and the vapor stream153 exiting the bottoms reboiler. Component process streams arerecovered as a portion of the liquid stream 154 exiting the condenserand a portion of the liquid stream 155 exiting the bottom of the unit.

Referring to FIG. 24, a method and assembly for utilizing CELLDISTmaterial 15 within a component separation unit to separate processstreams will be described. In this embodiment, CELLDIST material 15 isdisposed within the unit to replace some of the conventional trays 12 inthe unit. For example, large, bulky trays can be replaced with smaller,less complex trays, and the additional space that is created within theunit can be completely or partially filed with CELLDIST material 15 toachieve improved separation.

FIG. 25 shows a component separation unit according to the prior artcontaining conventional packing material 10. FIG. 26 shows an embodimentof the present invention using CELLDIST material 15, conventionaldistributors 11 and conventional packing 10 within a componentseparation unit.

The CELLDIST material 15 may be composed of any material that is capableof being fabricated into the required structure, and able to withstandthe temperature, pressure, corrosivity and other requirements ofcomponent separation unit operation. Inert CELLDIST material 15 can beused when no reactivity with the components in the process stream isdesired. In another embodiment, the CELLDIST material 15 is composed ofa non-metallic material in order to allow for treatment of corrosivesystems such as hydrochloric or sulfuric acid, to decrease design cost,installation time and to reduce heat loss in the unit.

The CELLDIST material 15 can take a variety of shapes with openlyconnected pores forming pathways or passageways 120 as illustrated inFIG. 27. The pathways in the CELLDIST material 15 allow thecountercurrent flow of phases through the material. Such pathwaysfacilitate mass transfer between the phases passing through the CELLDISTmaterials 15. The CELLDIST material 15 can be manufactured to exhibit awide range of porosity. This enables customization of the porosity ofthe CELLDIST material 15 for the specific application. Also, thisensures that the CELLDIST material 15 has sufficient mass and porosityto provide the number of theoretical stages needed to achieve thedesired separation of components in the unit. The CELLDIST material 15has web members 123 surrounding the pores, or openings, which in turndefine the boundaries of the flow passageways 120 (FIGS. 27 and 28).

Porosity of CELLDIST materials is measured in units of pores per inch(“ppi”). The porosity of porous materials is graduated as known to thoseskilled in the art. Microporous materials have the smallest pore sizes,generally from about five Angstroms to about five nanometers. Mesoporousmaterials generally have pore sizes of about five nanometers to aboutfifty nanometers. Macroporous materials have pore sizes in excess ofabout fifty nanometers. CELLDIST material comprised of macroporous poresor cells can have a random pattern as illustrated in FIG. 28. Theporosity range of the CELLDIST material 15 of the present invention isfrom about 4 to about 800 ppi. In a preferred embodiment for use in acomponent separation unit, the CELLDIST material 15 of the presentinvention will have a porosity of about 4 to about 30 ppi. The surfacearea of the interconnected pores in the CELLDIST material 15 facilitatesphase mixing and mass transfer within the unit. In one embodiment, theCELLDIST material 15 of the present invention advantageously provides anincreased surface area when compared to packing materials and other unitinternals used in the prior art. The surface area of the CELLDISTmaterial of the present invention of up to 4000 square meters per cubicmeter of CELLDIST material is in comparison to the approximately 60-750square meters of surface area per cubic meter typically provided inprior art unit packing internals. This increased surface areaadvantageously provides a more expansive location upon which contactingof the phases can occur. The corresponding increased level of contactbetween the phases results in improved separation capacity in the unit.The increased level of contact between the phases also results inimproved mass transfer efficiency and a lower HETP than prior art units.

In an embodiment of the present invention, phases are passed through oneor more zones of CELLDIST material 15 positioned within the unit, asillustrated in FIGS. 24 and 26. The process streams entering the unitcan be liquid streams, vapor streams, or a combination of both, and mayinclude one or more of, for example, a feed stream, a reflux stream, arecycle stream, a reboiled stream, a pumparound stream, a pump-backreflux stream and a sidestream recycle stream. A process stream can alsofunction as a mass-separating agent, as is the case in liquid-liquidextraction. Distillation using CELLDIST material 15 according toembodiments of the present invention can be accomplished at high gas orvapor loadings within a conventional unit.

In one embodiment, the CELLDIST material 15 is in the form of a singlestructured element, as illustrated in FIG. 27. The structured elementcan be shaped or sized to fit within the inner cross-section of thecomponent separation unit. The element can be, for example, a disk, anoval, a rectangle or any geometric shape that is required in order forthe material to fit within the cross section of the unit. Alternatively,if the unit has a relatively large cross-section, one or more smallersections of CELLDIST material 10 can be fitted together, as illustratedin FIG. 28, to span the cross-section of the unit. The CELLDIST material15 can form a single layer within the unit. Also, multiple layers ofCELLDIST material 15 may be utilized within the unit. The CELLDISTmaterial 15 can be laid in an offset pattern to decrease the likelihoodof leakage or channeling within the zone of CELLDIST material in theunit. One or more CELLDIST materials 15 can also be positioned over anentire length of a unit. Also, multiple CELLDIST materials 15 can becommingled throughout the unit with one or more conventional unitinternals, for example trays as shown in FIG. 24, packing material asshown in FIG. 26 or distributors, as shown in FIGS. 24 and 26.

There may be voidage, or open space, within the pores of, or surroundingthe exterior of, the CELLDIST material 15 in the unit. Typically, a highvoidage space or void fraction corresponds to a high porosity and a lowpressure drop within the unit, which is desirable for separationpurposes. The internal void fraction of the CELLDIST material 15 of thepresent invention is preferably as high as 70 percent. By comparison,the voidages found in most currently available metallic structuredpackings are about 98-99 percent, and are about 65 percent fornonmetallic structured packing. While certain of these prior artmaterials may have higher void fractions than that of the presentinvention, the increase in mass transfer efficiency associated with theincreased surface area of the CELLDIST material 15 of the presentinvention can allow the unit to be operated at a lower flooding number.This will preferably result in the same, or better, productivity for aunit operated with CELLDIST material 15 according to the presentinvention than a unit utilizing the prior art materials with highervoidage percentages.

The CELLDIST material 15 also exhibits good wettability characteristicswhen compared to prior art packing materials. Wettability relates to thelevel of contacting and distribution of phases on the surface of thepacking material and is affected by the structure of the material. Ahigh wettability value is critical for avoiding maldistribution ofphases within the unit.

In general, a packing material that achieves a high theoretical numberof stages at a given flooding factor with a low pressure drop is anefficient and preferred packing material. The goal is to minimize theamount of packing material used and yet produce the number oftheoretical stages that will result in the desired separation. TheCELLDIST material 15 of the present invention advantageously exhibitshigh separation efficiency and low pressure drop characteristics whencompared to prior art materials used in component separation units,which is a result of the increased surface area and preferred voidageand wettability characteristics of the CELLDIST material 15.

It is to be understood that the invention is not to be limited to theexact details of construction, operation, exact materials, orembodiments shown and described, as obvious modifications andequivalents will be apparent to one skilled in the art. For example,special liquid distributors or conventional liquid distributors could beused with the reticulated elements to facilitate the spreading of theliquid across process equipment. Conversely, the reticulated elementscould be used only for particulate removal. Accordingly, the inventionis therefore to be limited only by the scope of the appended claims.

The claims are as follows:
 1. A method of removing contaminants from acontaminated process stream comprising: a) providing a plurality ofreticulated elements within a process unit, wherein the reticulatedelements are sized such that there is a significant and varied voidspace therebetween, and wherein the entire depth of the randomly packedreticulated elements is capable of filtering contaminants from theprocess stream; and (b) contacting the contaminated process stream withthe reticulated elements to filter contaminants from the contaminatedprocess stream on a surface of the reticulated elements while allowingthe process stream to pass through the significant and varied void spacebetween the reticulated elements to produce a substantiallydecontaminated process stream, wherein the reticulated elements arerandomly packed in one or more layers extending along the interior ofthe process unit.
 2. The method of claim 1, wherein the one or morelayers span the extent of the process unit.
 3. The method of claim 2,wherein the reticulated elements have a pore size in the range of about2.5 millimeters to about 100 microns and are capable of filteringcontaminants from the contaminated process stream down to about 1 micronin size.
 4. The method of claim 3, wherein the reticulated elements havean internal surface area and an outer surface area, and the internalsurface area is larger than the outer surface area.
 5. A method ofremoving contaminants from a contaminated process stream comprising: a)providing a plurality of reticulated elements within a process unit,wherein the reticulated elements are sized such that there is asignificant and varied void space therebetween, and wherein the entiredepth of the randomly packed reticulated elements is capable offiltering contaminants from the process stream; and (b) contacting thecontaminated process stream with the reticulated elements to filtercontaminants from the contaminated process stream on a surface of thereticulated elements while allowing the process stream to pass throughthe significant and varied void space between the reticulated elementsto produce a substantially decontaminated process stream, wherein thereticulated elements are randomly packed in one or more uninterruptedlayers within the process unit.
 6. The method of claim 5, wherein theone or more uninterrupted layers span the extent of the process unit. 7.The method of claim 6, wherein the reticulated elements have a pore sizein the range of about 2.5 millimeters to about 100 microns and arecapable of filtering contaminants from the contaminated process streamdown to about 1 micron in size.
 8. The method of claim 7, wherein thereticulated elements have an internal surface area and an outer surfacearea, and the internal surface area is larger than the outer surfacearea.
 9. A method of removing contaminants from a contaminated processstream comprising: a) providing a plurality of randomly packedreticulated elements within a process unit, wherein the reticulatedelements are sized such that there is a significant and varied voidspace therebetween, and wherein the entire depth of the randomly packedreticulated elements is capable of filtering contaminants from theprocess stream; and (b) contacting the contaminated process stream withthe reticulated elements to filter contaminants from the contaminatedprocess stream on a surface of the reticulated elements while allowingthe process stream to pass through the significant and varied void spacebetween the reticulated elements to produce a substantiallydecontaminated process stream, wherein the process unit contains a bedof catalyst material, and wherein the pressure drop within the processvessel remains low for a predictable period of time based on the levelof contaminants in the process stream and the amount of the reticulatedelements provided in the process unit, and wherein the randomly packedreticulated elements in the process unit are provided in an amount suchthat during operations, the bed of catalyst material can be exhaustedbefore the reticulated elements are saturated, and wherein thereticulated elements have an internal surface area and an outer surfacearea, and the internal surface area is larger than the outer surfacearea, and wherein the reticulated elements have a pore size in the rangeof about 2.5 millimeters to about 100 microns, and wherein the randomlypacked reticulated elements are capable of filtering contaminants fromthe contaminated process stream down to about 1 micron in size.
 10. Amethod of removing contaminants from a contaminated process streamcomprising: a) providing a plurality of reticulated elements within aprocess unit, wherein the reticulated elements are sized such that thereis a significant and varied void space therebetween, and wherein theentire depth of the randomly packed reticulated elements is capable offiltering contaminants from the process stream; and (b) contacting thecontaminated process stream with the reticulated elements to filtercontaminants from the contaminated process stream on a surface of thereticulated elements while allowing the process stream to pass throughthe significant and varied void space between the reticulated elementsto produce a substantially decontaminated process stream, wherein theprocess unit contains a bed of catalyst material, and wherein thereticulated elements are sized such that the catalyst bed has exhaustedits catalytic activity before the reticulated elements become saturatedand have exhausted their ability to filter out contaminant particles,and wherein the pressure drop within the process unit does notsignificantly increase over a period of continuous operation.
 11. Themethod of claim 10, wherein the increase in pressure drop within theprocess unit is not greater than about 4% over 200 days of continuousoperation.
 12. The method of claim 10, wherein the increase in pressuredrop within the process unit is not greater than about 27% over 450 daysof continuous operation.